In most construction applications, two different types of foundations are used: shallow foundations (e.g., for a house); and deep foundations (e.g., for bridges, large buildings, and any structures on poor soils). When establishing deep foundations, the two most common systems conventionally used are: (1) cast-in-place concrete pile (commonly referred to as “auger cast pile” and/or “drilled shaft/pile”); and (2) driven, prefabricated (such as steel H or pipe, concrete or prestressed concrete). For example, cast-in-place pile systems are inserted into the ground by drilling a hole and filling the resulting hole with concrete, such as in a drilled shaft/pile. Prefabricated piles are driven into the ground using high impact forces from the driving system (e.g. hammer). Each type of deep foundation system has a number of advantages and disadvantages.
Conventional driven, prefabricated pile foundation systems generally improve the soil-pile resistance during driving compared to a cast-in-place pile. However, a driven pile can create substantial noise and ground vibration during installation—a process which must be carefully monitored so as to not impinge on the local environment. Furthermore, it is possible to damage prefabricated piles during driving, which may necessitate the costly and time-consuming removal and replacement of the pile. One way to avoid potential damage from and to a driven pile as well as reduce the noise generated from the pile driver is to use high pressure water to “jet” the prefabricated pile into the ground. While this process may be effective, the jetting process may also loosen the surrounding soil to such an extent that the pile's load-carrying capacity is substantially reduced.
Conventional cast-in-place systems (such as, for example, drilled shafts/pile and/or auger cast systems) limit potential damage to surrounding appurtenances (since very little energy is transmitted to adjacent structures) and are relatively quiet in operation. However, while cost effective and essentially impact-free during installation, conventional cast-in-place systems may result in a foundation that fails to retain its geometric properties (e.g., uniform diameter) because surrounding soil may fall away from the sidewalls of the hole or mix-in with the in-flowing concrete, which may substantially reduce the resulting foundation member's load capacity once the concrete has hardened. While these problems may or may not occur in a particular cast-in-place installation, it is very difficult to inspect or verify the condition of a cast-in-place foundation once it is installed. Therefore, confidence in a conventional cast-in-place foundation's design load-carrying capacity may never be assured.